An apparatus capable of switching displayed pictures in response to a slide gesture by a user includes a display screen for displaying an enlarged current picture, a touch determining unit, a picture processing unit, a control unit, a time calculating unit, and a calculating unit. The picture processing unit determines a width value of the current picture and a distance between a side of the current picture and an edge of the display screen adjacent to the side. The control unit controls the picture processing unit to obtain the target picture and controls the display screen to only display the target picture if a time duration of a slide gesture from beginning to ending is equal to or greater than a predetermined time period and a ratio of the distance to the width is equal to or greater than a predetermined ratio. A related method is also provided.